As discussed in other threads, looks like firmware v6.6 for the BMPCC 4k causes some batteries to no longer show a percentage (touching the battery icon in the top right just toggles between voltage and a blank).

It may be that the percentage display was never that reliable, but I like to discharge my batteries to be around 40-50% charged when placing them in storage when I anticipate not using them for a few months (as recommended by plenty of resources about long-term Li-ion storage).

I've got knockoff LP-E6N batteries with a stated capacity of 7.2V and 7.4V, but when fully charged they initially show up in camera with a charge of 7.8V or 7.9V. Basically, I'd like to know at which stated voltage the batteries are roughly at 40-50%. They go down to somewhere in the low sixes before the camera shuts off, but I'm not sure if the voltage display is "linear" so that slightly under the midpoint between 7.8V and 6.2V (or so) would be "40%". Any battery experts here with insights on a good voltage target?

(Anecdote: the first time I used the camera after upgrading, the battery icon was gone. I didn't know you could toggle between voltages and percentages, so I just assumed that the update had broken something... I was documenting a workplace party and trying to keep track of how long I'd used each battery for before having to change batteries. Managed to only get one camera shutdown due to low battery, and that was while it was idling rather than recording, so got lucky there )

I know it is a bit cumbersome, but why not just power the P4k with a power pack? With that, one never has to worry about power. The camera indicates AC, everything is alright. And if anything goes wrong, there's always the internal battery that keeps the camera alive for half an hour or more. Enough time to attach another power pack and charge the internal battery while the camera is on, or rolling.

I apply the same principle to the P4k that I use since many years with my iPads: internal battery is just plan B, backup. The main power source is always external. My iPads from 2012 are still in good condition with only few dropdowns to 0% or power cycles. I expect them to maintain their capacity for another 8 years.

Phil999 wrote:I know it is a bit cumbersome, but why not just power the P4k with a power pack? With that, one never has to worry about power. The camera indicates AC, everything is alright. And if anything goes wrong, there's always the internal battery that keeps the camera alive for half an hour or more. Enough time to attach another power pack and charge the internal battery while the camera is on, or rolling.

I mean, sometimes I do, depending on where I'm operating and how lightweight I want to be. If I'm traveling and want to fit the camera into as small a space as possible for my day bag, I'll rely on the internal batteries exclusively. (Three or four of them get me through a full day's shooting needs.)

But my question was specifically about discharging batteries to a specific target for long-term storage with the aid of the camera's voltage indicator, which is a different issue.

JK Laiho wrote:But my question was specifically about discharging batteries to a specific target for long-term storage with the aid of the camera's voltage indicator, which is a different issue.

this is a difficult topic. Because there appears to be no clear directive about how to handle lithium-based batteries. Companies that specialise in (larger) lithium batteries like Zero Goal or Sistech recommend to keep the charge as high as possible. Recharge every 3 months if not in use.

We often don't know what specific lithium battery type is used in our gear.
https://batteryuniversity.com/learn/art ... ithium_ion

I believe, but don't know for certain, that as a general rule one should keep a lithium-base battery charged as often as possible. For storage one can leave the fully charged battery as it is, it will lose some of its charge over time, and when it goes below 70% it is time to recharge.

I could expand on this because I rely much on these types of batteries, I lived for several years (except December to April) in the forest with portable solar systems to power tablets, synthesisers, cameras, lights, etc.